Venting device for die casting machines



Jan. 13, 1959 F. HoDLER 2,867,869

VENTING DEVICE FOR DIE CASTING MACHINES Filed Jan. 20, 1958 5Sheets-Sheet 1 Jan. 13, 1959 F. HODLER 2,867,869

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VENTING DEVICE FOR DIE CASTING MACHINES Filed Jan. 20, 1958 5Sheets-Sheet 3 I I Ax T v \n In Fig.4

Jan. 13, 1959 F. HODLER 5 VENTING DEVICE FOR DIE CASTING MACHINES FiledJan. 20. 1958 5 Sheets-Sheet 4 2,867,869 I VENTIN G DEVICE FOR DIE (JASTING MACHINES Fritz Hodlery Territet, Switzerland Application January 20,1953, sen-n No. 710,085 Claims priority, application Switzerland October1, 1957 6 class. (or. ag le) The present invention relates generally to.die casting machines and more particularly .to improvements in ventingdevices for dies in die casting machines of the type in which the diehas means for evacuating the air and gases from the die cavity. Theevacuating means are characterized by the use of valve means designed tobe closed when the die cavity is filled with metal.

Die casting machines of this general type are Well known in the priorart and having been described in my prior U. S. Patent #2,785,488.

Although the valves controlling the evacuation of the dies of themachines of the prior art operate satisfactorily, their mounting on oneof the die 'halves offers certain difiiculties because of lack ofconvenient space and because of unfavorable heat conditions which tendto deteriorate the packing used in these valves. Furthermore any repairor maintenance work on the valve necessitates taking the die half fromthe machines, which especially in the case of large sized diesis a greatinconvenience.

It has been found that although the adaptationof the valve to the die isgenerally possible in the case of new dies which can be designedaccordingly, this adaptation is often'unpractical'in the case ofexisting dies'in current use which are quite hard and extremelydifficult to machine. Also any machining or welding of hardened diescarries the risk of setting up new tensions and distortion which should,of course, desirably be.

avoided; Q

The object of the present invention isto avoid these inconveniences bythe use of' a -valve which is dependent of the die and not connectedwith the same, this valve being mounted on the frame of the die "castingmachine. The valve is provided with means for bringing it into contactwith the die prior to the casting operation, and for moving it away fromthe die When the injection is terminated. The valve is also providedwith means for controlling these movements and for allowing the air andgases to be evacuated from the die cavity and has means for insuring theclosing of the air channel of the die at the required i time during theinjection cycle. A further advantage of my invention 'is' then in orderto adapt a die to be used in connection with this valve, only asmallchannel has to be ground in the die, which is possible also inthe'case of hardened dies, and also regulation of the closing time ofthe valve may be made possible without removing the die from themachine. f

Another advantage of my invention is that maintenance and repair 'ofthevalve is greatly facilitated since the valve forms a separate unitattached to the die casting machine. -It is also clear that the samevalve can be used in connection with a great number of dies. Also thevalve can be mounted on the frame of the machine at any place to suitthe design and the size of the die.

Still another advantage of my invention is that the I ited Patentcapacity of the air passage can easily be adapted to the volume of thedie and the die cavity in order'to in tion when the die as Well as theventing device are closed.

Fig. 2 shows diagrammatically one of the die halves with an air outletchannel.

Fig. 3 shows the same arrangement as Fig. l, but in the position whenthe die is open.

Fig. 4 shows diagrammatically a horizontal section of the venting devicein the position when the die is open.

Fig. 5 shows the same section as Fig. 4, but in the position when thedie is closed, but before the valve is closed.

Fig. 6 shows the same section asFigs. 4 and 5, but in the position whenthe valve is'closed; 1

Referring to'Fig. 1 the pressure die casting machine consists of a framel on which is mounted the die 2 consisting of the two die parts 3 and 4.These parts 3 and 4 are held together by means of a locking device. Thisdevice, which in general has a toggle mechanism, is by Way ofsimplification shown as a hydraulic cylinder 5, in which thedifferential piston 6 can slide, this piston acting through a rod 7 on alocking member 8, which is designed to hold the part 3 tightly pressedagainst part 4 of the die which itself is fixed to the frame of themachine. This locking member 8 is in general supported by rods (notshown) which slide in hearings in the frame of the machine. Part 3 ofthe die has bores for the rods 3a of an ejecting device which is knownand is therefore not shown in detail or described.

The frame 1 has an injection sleeve 9 in which the molten metal canbepoured through the opening it). This metal can be pressed in thecavity 11 of the die 2 by the injection piston 12, which, by means ofthe rod 13 is connected to the plunger 14 which slides in the cylinder15.

The piston 6 and the plunger 14- are actuated by hydraulic pressurewhich is supplied from the control station '16 of the machine by aconduit system to the cylinders 5 and 15. Fluid under pressure, which byway of example may be supplied by a pump, is supplied to the controlstation 16 of the machine by means of conduit 17. From here the conduit18 connects the con trol station with the cylinder 5 in order to applypressure to one face of the piston 6 to effect closing of the die 2 Bymeans of conduit 19 liquid under pressure is fed without interruption tothe opposite face of the piston 6 in order to cause opening of the die2. A conduit 24 connects the control station 16 with the cylinder 15 inorder to feed liquid under pressure into it during the injection phase.to feed liquid under pressure to the plunger 1 in order to make it movein the opposite direction when the injection piston is to be returned toits initial positon.

A conduit 21 is designed 1 This channel 22 is 3 channel 22 so as to shutoff this channel as soon as the die cavity 11 is filled with moltenmetal.

In the example given, this valve 24 is operated by hydraulic pressure bymeans of the conduit '25 connected to the conduit 20 in the mannerdescribed in the machine in such a manner as to allow it to be broughtinto contact with die 2 during the casting opera- 1 tion and to beremoved from the die 2 after the casting operation. Suitable controlmeans are provided for bringing the valve 24 in the required closingposition of the channel 22 at the desired moment during the castingoperation.

lever 26 from the position I to position 11, liquid under In thearrangement shown by way of example in Figs. 8

4-6, the valve 24 is located at the interior of cylindrical member 28,which has the general shape of a bell. This member 28 forms part of thecentral body 27 and has a face 29 designed to be brought into closecontact with the die 2 during the casting operation in such a manner asto surround the orifice 30 of the air escape channel 22.

As shown in Figs. 4-6, the movable central body 27 forms a differentialpiston with one face of larger diameter 32 and on the opposite side aface of smaller'diameter 31. This differential piston 27 slides in thecorresponding cylinder 33 which forms the main valve body,

which body is fixed to frame 1 of the machine by means of the lugs 34.The bore 35 of the cylinder 33 in which slides the face of the smallerdiameter 31 of the differential piston 27, is closed by means of thescrew plug and the differential piston 27. The guide ring 43 issupported by the screw ring which is threadably mounted in the cylinder33. The bore 39 of cylinder. 33 is connected with conduit 19 by means oflateral opening 46 in the cylinder wall and conduit branch 46.

The valve 24 consists of a rod actuated by a piston 47 sliding in acylinder bore 48 of the central body 27. This cylinder bore 48 is closedat its extremity by the bell-shaped member 28 which has a threadedextension 49 screwed into bore 48. The piston 47is held in the openposition of the valve 24 under the influence of spring pressure, showndiagrammatically as a single cylindrical helical spring 50. Regulatingmeans make it possible to vary the force exercised by the spring 50. Inthis particular case these regulating means consist of a screw bushing51 which is screwed in the central part of the bell-shaped part 28 andwhich contacts one end of the spring 5%. The exterior part of thisbushing 51 is j shaped in such a manner that it can be rotated by meansof a suitable tool to adjust the position of the bushing longitudinally.

A channel 53 is provided in the wall of central body 27 and connects theleft hand part of the cylinder 48 with t the conduit 2% by means ofcoupling 54 and branch line i The piston 47 has a pressure tight packing55. j The face 29 of the bell-shaped member 28 is formed by member 56which is screwed'onto the body of the bell-shaped member 28. A filter 57is fastened intermediate parts 28 and 56 and has an opening in themiddle thereof through which the valve rod 24 can pass.

As shown in Figs. 4-6, the valve 24 is arranged in such a manner as tohave its longitudinal axis parallel with the contact surface 58 of thedie halves 3 and .4 of the die 2, this axis being perpendicular to theem 59 of the die in which the channel 22 is located.

The operation of the machine described above may now be readilypresented:

When the operator of the machine moves the control pressure will flow inconduit 18. The piston 6 will then be moved to the right against thepressure of the liquid acting on the other face of the piston 6 suppliedthrough conduit 19 to cause locking member 8 to be displaced so thatparts 3 and 4 of the die 2 are brought intocontact with one another; Atthis moment the pressure in tudinal displacement of thedilferentialpiston 27 and of the bell-shaped member 28 thereon toward the face 59 ofthe die 2. This hydraulic pressure in the cylindrical part 35 exercisesa strong pressure on the bell-shaped 'member 28 to firmly. force itagainst the face 59. Ring 61, which maybe formed from aluminum forexample,v

ensures a pressure tight joint between the faceof the bellshaped memberandthe face 59 of the die 2. p

The conduit 23 which is in communication with .the interior of thebell-shaped member 28 by means of a channel 62 enables the vacuuminstallation 64 to create a vacuum in the cavity 11. As soon as theoperator has poured a quantity of molten metal intheinjection sleeve, hemoves the control lever 26, from position II to position III. In thisposition theconduit 18 .is always under pressure to ensure locking ofthe die halves 3 and 4 and conduit 20 transmits fluid under pressure.The actual injection phase commences by the'displacement ofthe plunger14 in the cylinder ,15, which causes forward movement of the injectionpiston 12 in sleeve 9 toward the die part 3. The pressure in conduit 25will also be increased but valve 24 will not be moved to a positionclosing channel 22 until the pressure in conduit 25 reaches a valuewhich is greater than the spring force exercised by the spring 50. Sincethis force can be adjusted by H means of the bushing 51, itispossibletochose the-moment of the closing of the channel 22 by thevalve 24 59 to close the orifice of channel 22 as shown in Fig, 6.]

When the injection phase -is terminated the operator will bring thecontroljlever 26 from position 111 to po-,

sition I. In this position thehydraulic fluid in conduits 18 and 20 canescape through conduit 60, whereasjtheconduit 21 is filled with fluidunder pressurc. ThQP essure which is continually exercised on the face32 of the differential piston 27 and on the face of smaller diamv eterof the differential piston 6' by fluidfiin conduit 19 and conduit branch46? then causes a displacement of the piston in the opposite direction.The ratio of the surface area of the two opposed faces of thedifferential piston is chosen in such a manner as to cause thedifferential piston 27 to be removed from the die 2 before thetwo dieparts 3 and 4 are moved apart in avoid possible wear of the ring 61.

When the fluid in conduit 20 isallowed to escape; a

lowering of pressure will occur at the same time in the conduit 25 toreturn valve 24 to its initial position.

order to Moreover, the pressure acting in the cylinder 15 through theconduit 24 will bring the injection piston 12 also back to its initialposition. The casting can now be removed from the die cavity 11 and themachine is ready for another casting operation cycle.

The manner in which this venting device is designed and arranged can bevaried in numerous ways without departing from the spirit of theinvention. For instance, the differential piston 27 can be brought backto its initial position by means of hydraulic pressure acting continuously in bore 39, or under the influence of the force of a spring.The displacement of the piston 27 towards its forward and activeposition may be effected by other suitable pneumatic, electrical orpurely mechanical means. Similarly the control valve 24 can be effectedby suitable hydraulic, pneumatic, electrical or mechanical means whichmay or may not be independent of the circuit which controls theinjection phase of the piston 12.

The special arrangement of the valve 24 which controls the escapechannel 22 may be applied to a pressure die casting machine which is notprovided with a vacuum installation 64.

The special arrangement of the valve 24 described above with referenceto the annexed drawings is by way of example shown on a cold chamberpressure die casting machine of the horizontal type. It is clear thatthis arrangement of the valve 24 can be applied to any other type ofpressure die casting machine either hot or cold chamber and with eitherhorizontal or vertical injection piston.

While in accordance with the patent statutes I have described andillustrated the preferred embodiment of my invention now known to me, itWill be apparent to those skilled in the art that other changes may bemade in the apparatus described without departing from the scope of theinvention set forth in the appended claims.

I claim:

1. A venting device for die casting apparatus of the type having a pairof relatively movable die elements having opposed die faces betweenwhich is formed a die cavity, at least one of said die faces having achannel therein for evacuating air and gases from the die cavity,comprising valve means secured to the die casting apparatus adjacent andspaced laterally from the die elements, said valve means having alongitudinally movable sleeve therein, means for moving said sleevelongitudinally to cause one end thereof to come into contact with bothdie elements about the orifice of the die face channel prior' to thecasting operation and for moving said sleeve away from the die elementswhen the injection of material into the die cavity is terminated,passage means within said movable sleeve adapted to be connected to avacuum source for allowing air and gases to be evacuated from the diecavity when said sleeve is in contact with said die elements, and avalve element within said movable sleeve for closing the die channel ata predetermined time during the injection cycle to prevent ejection ofmaterial from the die cavity.

2. In a die casting apparatus a venting device as defined in claim 1wherein said movable sleeve comprises a difierential piston.

3. .In a die casting apparatus a venting device as delined in claim 2wherein the end of said differential piston adapted to contact the dieelements has a cavity therein in communication with means for evacuatingthe die cavity.

4. In a die casting apparatus a venting device as defined in claim 3wherein the means for evacuating the die cavity includes vacuum means.

5. In a die casting apparatus a venting device as defined in claim 3wherein said valve element includes a longitudinally-movable valvepiston colinearly arranged within that end of the difierential pistonwhich is adapted to contact the die, said longitudinally-movable pistonbeing adapted to close the orifice of the die channel and thus terminateevacuation of the die cavity.

6. Apparatus as defined in claim 5 and further including spring means insaid movable differential piston biasing said valve piston out ofengagement with the orifice of the die face channel, and bushing meanssurrounding the shaft of the valve piston for adjusting the tension ofsaid spring means.

References Cited in the file of this patent UNITED STATES PATENTS

